textproduct: Rapid City

KEY MESSAGES

- Elevated to critical fire weather conditions Friday afternoon - Cold front late Friday brings colder temperatures for the weekend along with some light snow over northwestern South Dakota

DISCUSSION

(Tonight Through Thursday) Issued at 1037 PM MST Thu Feb 26 2026

05z surface analysis had a low near CWEQ with a trailing cold front into southern MB. Water vapour loop had northwest flow over the CWA with a shortwave over south-central Canada and another popping into northern BC. In the near term, the main concern will be Fire Weather Friday.

Tonight/Friday, cold front sags southward as it enters far northwestern SD late Friday afternoon. Well-defined boundary layer mixing ahead of the front will bring gusty northwest winds (40-80% chance >30mph gusts) to much of the area, especially from northwest into south-central SD. Temperatures will be near guidance and relatively mild.

Friday night/Saturday, cold front moves through the area, likely stalling/bisecting the CWA Saturday. Moisture will be very limited ahead of the front, but as the northern BC shortwave dives southeast with weak QG-forcing/but well-defined post frontal low level frontogenesis, expect a band of snow to breakout near the SD/ND border, centered northeast of the CWA. Latest HREF guidance shows 60-80% chance 0.1" QPF, but <30% chance >0.25" QPF. Still quite a bit of spread of where the best snow totals will reside, so confidence low for our area. Highs Saturday will have quite the spread given uncertainty in cold front position, but certainly colder. Saturday night/Sunday morning, upslope flow (low clouds/fog?) may develop as cold high pressure over the Great Lakes funnels easterly component to boundary layer wind into the area.

For next week, split flow dominates with a warming trend and minimal chances for impactful precipitation. Perhaps after the forecast period, a better defined upper trough develops over the western CONUS.

AVIATION

(For the 12Z TAFS Through 12Z Saturday Morning) Issued At 351 AM MST Fri Feb 27 2026

VFR conditions are expected through the period. Gusty northwest winds will develop across western South Dakota later this morning with gusts of up to 35 kt expected across northwestern South Dakota.

FIRE WEATHER

Issued At 1037 PM MST Thu Feb 26 2026

Very dry air will affect parts of northeastern Wyoming as well as far southwestern into south-central South Dakota Friday afternoon. Minimum relative humidities will drop to 15-20 percent as northwest winds increase to 10-25 mph with gusts from 25-40 mph, strongest over south-central South Dakota. The joint probability of MinRH <=15%/frequent wind gusts >=25mph Friday afternoon over the far southwest reaches of the CWA is 30-50%. Antecedent D1 to D2 drought conditions will exacerbate the fire potential. The combination of low humidity values and gusty winds will create critical fire weather conditions on Friday for these areas.

Elevated fire weather conditions are expected over the rest of northeastern Wyoming and northwestern South Dakota Friday afternoon. A cold front moves through late Friday bringing cooler temperatures Saturday/Sunday with limited precipitation chances, except for locations near the North Dakota/South Dakota border where light snow accumulation may develop.

UNR WATCHES/WARNINGS/ADVISORIES

SD...Red Flag Warning from noon MST /1 PM CST/ today to 6 PM MST /7 PM CST/ this evening for SDZ322-326-333>335. WY...Red Flag Warning from noon today to 6 PM MST this evening for WYZ315-317.